I Have Pulled A Muscle/tendon/something In My Groin Area. I'm

I have pulled a muscle/tendon/something in my groin area. I'm morbidly obese and this happened when I tried to pick something off the floor. Now I find getting up and sitting down extremely painful. I use a walker for chronic arthritis in my knees, but the walker doesn't seem to provide any relief. I already take Lyrica for my knees (I have to lose weight before I can be a candidate for knee replacements), should I take Motrin, too? I also take Sulindac for inflamation (my knees aren't the only body part effected by arthritis). What can I do to relieve the pain so I can pick up my son and go to Christmas Dinner at my daughter's house tomorrow? Extreme pain when I try to get up from a seated position, or sit from standing. Thanks for your helps.